Integrated Pest Management for Raspberries

Harvest Period

Acknowledgements

Nooksack IPM Advisory Committee

Introduction

Dormant and Pre-Bloom

Bloom/Pre-Harvest

Harvest Period

Key Pests
Biology
Monitoring
Scouting Report
Matrix - Insects
Matrix - Diseases

Post-Harvest

Insect Identification Sheets

Disease Identification Sheets

Tables and Charts

Pesticide Selection

IPM Resources

Pesticides and Water

Biology

Insect Contaminants in Machine Harvested Raspberries
Many insects are dislodged from raspberry foliage during the machine-harvesting process. These may include leafrollers, loopers, cutworms, small gnats, plant bugs and several different species of weevils. Spiders are often present as well. Many of these insects do not directly damage the plant but their mere presence in harvested fruit can pose a contamination problem. The most serious contaminants are weevils and a variety of cutworms. Most of these insects are adequately controlled with an insecticide application prior to the onset of harvest.

Black Vine Weevils (Decision Making Guide) (Images)
Most black vine weevil (BVW) adults have emerged from the soil by the beginning of harvest. Peak emergence is usually in late May to early June. Above ground foliar feeding from BVW does not usually cause significant damage to raspberry plants but if not controlled prior to harvest, adult weevils are a serious harvest contaminant. In addition, egg laying will occur during harvest which allows for a continuing larval infestation and subsequent adult population the following season.

Spider Mites (Decision Making Guide) (Images)
All stages of spider mites (eggs, immatures, and adults) are likely to be present during the harvest period. The length of time required to complete one generation depends primarily on temperature and can be as short as 10 days during warm summer months. Spider mite populations can therefore increase rapidly if weather is hot and spider mite predator populations are low. The most common mite predators in raspberries include Stethorus beetles, minute pirate bugs, and predator mites.

At this time of the year, spider mites are found on primocanes as well as floricanes. They are more commonly found on older or mid-shoot leaves rather than on the newer growth. Feeding on the underside of leaves initially causes a white speckling appearance to the upper leaf surface. High populations and extended periods of feeding can cause leaves to appear bronze in color. This bronzing is due to water loss from foliage.

Botrytis Fruit and Cane Rot (Decision Making Guide) (Disease Cycle) (Images)
It is during the harvest period that this disease becomes active as the fruit matures. Symptoms include gray mold on the surface of berries and pale brown lesions on the surface of canes. Disease develops faster on overripe mature berries.

Cane Blight (Decision Making Guide) (Disease Cycle) (Images)
Old infected floricanes are the primary source of inoculum which can infect primocanes wounded during harvest. External symptoms are usually not visible on primocanes during harvest. Suspect areas should be checked closely in the fall by scraping away epidermis of primocanes near wounds. In infected canes, a reddish streaking lesion within the vascular tissue can be seen at that time. This is not a commonly occuring disease in the Pacific Northwest, but if present can be quite serious.

The harvest period is a critical period for cane blight because catcher plates on harvest machines, if not adjusted properly, can damage primocanes and open the door for infection. Cane blight symptoms cannot be seen until later in the fall.

Spur Blight (Decision Making Guide) (Disease Cycle) (Images)
Spur blight infection of new canes first appears as brown, wedge-shaped lesions usually on lower primocane leaves. The fungus progresses through the leaf and petiole, and into the primocane where it causes a chestnut-colored lesion on the surface around a bud. This cane lesion is the most obvious symptom of the disease during the harvest period.

Phytophthora (Decision Making Guide) (Images)
The most common above ground symptom of Phytophthora root rot during the harvest period is the collapse of fruiting laterals and wilting of primocanes. The pattern of diseased plants is determined by the presence and movement of the disease organism in the soil. Root rot caused by Phytophthora fragariae var. rubi can be found in both well-drained and poorly drained soils.

Monitoring

JULY AND EARLY AUGUST

Insect Contaminants in Machine Harvested Raspberries

Harvesting machines are one of the best insect monitoring tools.

• Ride the harvesters to see what insect contaminants, if any, are coming across the belt. This is one of the best methods to evaluate the effectiveness of your pre-harvest clean up spray.
• Detection of weevils on the belt indicates that either sprays were not effective or that adult weevils are continuing to emerge.
• A spray should be applied to control adult weevils if they are contaminating fruit so that they are controlled before egg laying occurs. This will also help reduce the population in the following season.
• Most other insects can be removed from the sorting belt by hand as long as they are not too numerous.
• Consider making adjustments in your mechanical harvester to reduce problems.
• Sprays may be necessary to control a variety of cutworms and leafrollers when they are too numerous to be removed from the belt; this is more common in the last couple of weeks of harvest when obliquebanded leafrollers and miscellaneous cutworms may be present at troublesome levels.
• A single clean up spray to control insects is generally all that is required to achieve effective control through the harvest period. Make sure to check pre-harvest intervals closely on any pesticides used during the harvest period.
• Continue to use beating trays every two weeks or so to assist with observations made from harvesting machines.
• If peak OBLR (obliquebanded leafroller) flight is delayed until just prior to or after the start of harvest, inspect hills as described in previous section to determine the percent leafroller infested hills. Greater than 10% infestation may warrant control. The bacterial insecticide, Bacillus thuringiensis (B.t.) is effective if timed properly. It has an advantage for use during harvest due to its short, one day PHI (pre-harvest interval).

Spider Mites (Decision Making Sheet) (Images)

• Mite populations can often remain very low during the early summer and then increase rapidly during harvest.
• Continue to examine leaves for mites and mite predators as well as the bronzing damage spider mite feeding can cause to leaves.
• Check fields every ten days to two weeks.
• Consider the following before applying a miticide:
• Has the spider mite population increased since the last visit?
• Are there lots of eggs...potential for rapid increase under hot conditions.
• Mite populations can increase more rapidly in drip-irrigated fields and under dusty conditions.
• Are mite predators present at most sites; are they on the increase.
• Is mite damage restricted to just part of the plant or does it appear to be spreading.
• Is there an effective miticide available with a short PHI (one to two days).
• A miticide application may be necessary during harvest if you think the spider mite population is on the rise and the material has a short PHI. Control is usually better if it is timed to catch a building population rather than one that has gotten out of hand.
• If you apply a miticide, resample about 5 days after the application to determine how effective the spray was.

Botrytis Fruit and Cane Rot (Decision Making Sheet) (Images)

• Fruit should be picked frequently where there is much gray mold seen, particularly under wet conditions and in fields with heavy canopies which are slow to dry out.
• Berries infected by Botrytis are usually not shaken off the plant by the harvester, hence you will not get an estimation of disease severity by inspecting berries as they come across the belt. Check fruiting laterals for the infected berries. If disease incidence is too high, consider applying a fungicide with a short pre-harvest interval (PHI).
• Meekers are strongly resistant to cane infection, but some other varieties like Comox are quite susceptible.
• Cane lesions can girdle primocanes and fruiting laterals in some cases. Don't confuse Botrytis cane lesions with spur blight. Look for tan lesions (much lighter in color than spur blight).
• Additional fungicide applications during harvest may be necessary in some situations.
• In most cases, these diseases are controlled with the bloom fungicide applications, but remember to check occasionally during harvest. Observations at this time will help evaluate the pre-harvest fungicide program and point to possible need for sprays during harvest.
• Botrytis is more likely to be a problem in wet years and in fields with heavy canopies that are slow to dry out following irrigation or rainfall. Cultural practices to reduce Botrytis problems include:
• Avoid applying excessive amounts of nitrogen.
• Control weeds to improve air movement within the canopy.
• Good primocane suppression.
• Shorten intervals between picking if practical.

Cane Blight (Decision Making Sheet) (Images)

• Adjust catcher plates on mechanical harvesters to minimize wounding.
• Consider applying a fungicide directed at the base of canes in infected fields.

Spur Blight (Decision Making Sheet) (Images)

• Examine primocanes for spur blight lesions, which appear as dark brown areas on the cane around the bud. Petioles may be left attached to the cane.
• Fungicides with a short PHI are available for use during harvest where these symptoms are seen.

Phytophthora Root Rot (Decision Making Sheet) (Images)

• Above ground symptoms of this disease are most evident just prior to and during harvest. Look for reduced number of primocanes, wilted primocanes, and fruiting canes with yellow or scorched lateral shoots. These symptoms are more likely to be found in low areas where saturated soil conditions persist, which favors infection and spread of the disease.
• Poor growth in low-lying areas may also be due to anaerobic (low oxygen) conditions which are unfavorable for normal root function. Phytophthora may not even be present, yet plants show symptoms typical of Phytophthora infection. In this situation, application of fungicides targeting Phytophthora is obviously not appropriate.
• Pull up some plants and examine the crown area by scraping away the epidermis, which will reveal a distinct margin between healthy (white) and disease (red) tissue, if infected with Phytophthora. A lack of fine feeder roots is also associated with Phytophthora root rot.
• Presence of both the above ground and root/crown symptoms indicates that Phytophthora is the causal agent and that fall and possibly, spring soil-applied fungicides may be appropriate.
• Confine treatment to those areas where scouting indicates a problem and lab results confirm presence of the pathogen.

Scouting Report - Harvest Period (PDF File)